Consumer unit keeps tripping

[crank39]

Came home from work tonight to find it tripped out, it did this a couple of years ogo but i managed to isolate the problem by individually isolating each circuit that the RCD protects, turned out to be a failed heater element in the water tank.

The RCD protects the cooker, upstairs and downstairs sockets, water heater and shower.

So tonight, one by one i isolated the water heater and it still trips, isolated the cooker, still tripped, unplugged kettle, microwave and everything else i could apart from the TV/DVD etc etc and it still tripped, funny thing was it wasn't tripping straight away, it would take 5 mins then trip out, it did manage to last about an hour earlier but now with a stopwatch it lasts dead on 5mins, each time, tried it 4 times with same result.

What could it be?

 

[PrenticeBoyofDerry]

Did you isolate shower?
Any signs of damage and possible water ingress on the shower control enclosure?
You really need to unplug everything as an item of equipment can be responsible.

 

[crank39]

Prentice, isolated everything one by one, cooker, shower, heater but still tripped, but why take 5 mins to trip???

Anyway, i've isolated the sockets and its lasted 40mins so far so it appears its something thats still plugged in although i unplugged loads of stuff it was still tripping but i didn't unplug the tv/dvd and all that jazz you have behind the tv, also the PC, printer, table light, phone charger

 

[ricicle]

Faulty outside lighting spurred from a socket circuit ? A photocell is initialising and then switching on ? Faulty boiler via a fused spur (you haven't disconnected it) and the faulty part of circuit is switched after a set period or initialisation ?
Some other faulty appliance connected via a fused spur that you have forgotten ?

Edit: Just read your last post.

 

[PrenticeBoyofDerry]

The best method is the process of elimination, so without unplugging everything one by one it would be difficult to diagnose.
It sounds very much that it is something that is on-load and plugged in.

 

[ericmark]

RCD's trip on imbalance between live wire wires which includes the neutral.

For line to earth leakage switching off items will soon find the problem but with a neutral to earth leakage it becomes far harder.

The problem is where it's not a direct short but just a small about of leakage between neutral and earth the more current that is drawn from the circuit the greater the difference between neutral voltage and earth voltage so the more current will leak.

So if for example the problem was an old TV before double insulated was used. This can run without problem on it's own as the voltage difference between neutral and earth is very small. However plug in the kettle and the RCD trips because of the increased difference in neutral and earth voltage. There is nothing wrong with the kettle it's the TV at fault but since it trips when kettle is plugged in the kettle gets the blame.

So two pronged attack to find the problem.
1) Don't just switch off also unplug items so the neutral is also disconnected.
2) When you find something suspect try it on another circuit and see if fault moves.

One problem is the lights are now on earth leakage but the MCB and light switch is single pole so neutral is still connected. So removing light bulbs on all non double insulated fittings. You may wish to disconnect the kitchen florescent fitting to test if that has a problem.

But there is a limit to what can be tested without meters. And one has at some point realise you need an electrician with his meters to test and isolate the cause.

Personally I would like to see double pole MCB's in RCD protected circuits so one can turn off the neutral but cost has resulted in just single pole. So good luck but I would set your self a time limit and if not found by that time then call an electrician.

Even as an electrician I have spent hours looking for faults. There are some once found never forgotten like freezers with auto de-frost (Or frost free as it now called) where a timer switches on a heater every so often if this becomes faulty can be really hard to find. Often end up with an extension lead and power it from upstairs and see if fault swaps. Even the meters have a problem finding that one would need to strip down freezer to test.

 

[crank39]

BLIMEY

Anyway, i shall carry on unplugging, see what i come up with

Thanks with all your help so far guys, much appreciated

 

[crank39]

Bit of an update, tracked it down to the 1 year old washer/dryer, unplugged that a couple of days ago and it stopped tripping.

But heres the thing, having plugged it back in it mysteriously stopped tripping which made me think it was in fact the wine cooler, both of which were in the same socket doubler behind the washer. Just put a wash on and as soon as the drum starts to turn it trips yet while just plugged in its ok YET the other night it was just plugged in and kept tripping

What is going off with my electrics?

 

[RF Lighting]

Sounds like something has dried out a bit.

It's time to get someone in with an insulation resistance tester.

 

[Chri5]

Have you pulled out the washer and checked under for signs of water? Maybe there a split /leaky hose or seal dampening inside the machine.

Take the back off and check any wiring terminals. A tissue test works well, the idea being that touching the tissue in areas that should be dry is a better test than simply feeling with your hands for wet and dry as the tissue will get wet and seen.

Check the plug pins, and having isolated, look inside the socket. Wires should be clean.